CSI: Demon's In Sin City
by JoannaKuwabara
Summary: CSIYYH Warnings inside Las Vegas crime lab appeared on a murderkidnapping scene. The clues that were left behind seemed to put their logic to the test as what they couldn't make any sense of what happened. more summary inside UPDATED! Chapter One is up!
1. Chapter 1

**CSI: **

**Sin City's Demons**

**Crossover: **

**CSI: Crime Scene Investigation**/ **Yu Yu Hakusho**

**Pairings: (_Seme/ Uke)_**

Yusuke Urameshi/ Kazuma Kuwabara

Hiei/ Kurama

Koenma/Botan

Shizuru/Yukina

OC/Kuwabara – _one sided by OC_

Gil Grissim/Genkai

Nick Stokes/ Greg Sanders

Sarah Sidle/ Warrick Brown/ Catherine Willows

**Mentions/ Hints: **_(past tense)_

Yusuke Urameshi/ Keiko Yukimura

Keiko Yukimura/ Kazuma Kuwabara –_rape on Keiko's part_

Gil Grissim/Sarah Sidle

The following **Disclaimer **applies for this as well as all future chapters.

**Yu Yu Hakusho- **All rights reserved to:**Shonen Jump Graphic Novels**, **Viz**, **Funimation**, **Shueisha Inc**., and **Yoshihiro Togashi **I do not own Yu Yu Hakusho nor its characters, mangas, anime, or anything related to it in anyway. I am not making any profit from using it in this story.

**CSI: Crime Scene Investigations**- All rights reserved to: **CBS Productions**, **Alliance Atlantis Productions**, and **Jerry Bruckheimer** I do not own **CSI **nor its actors, characters, or anything related to it in anyway. I am not making any profit from using it in this story.

**Summary: **

When the Las Vegas crime lab appeared on the scene of a murder scene, they learned it was also a kidnapping. Yusuke Urameshi is the main suspect in his ex-girl friend's murder, and to top it all is his bf Kuwabara was kidnapped. How can he explain he didn't commit the crime but it was a demon? X-over, yaio, yuri, violence, language, M for Mature audiences

**Full Summary:**

When the Las Vegas crime lab appeared on the scene of a murder scene, they learned it was also a kidnapping. As they look through the clues that were left behind, they find that their logic is put to the test as what they find doesn't make any sense to what they know to be real about '_demons_' and '_monsters_'. On top of that, one of their new recruits, Shuuichi Minamino, has emotional ties to the case and threatens to compromise the entire investigation not to mention his job.

Yusuke Urameshi is the main suspect in his ex-girl friend's murder, and to top it all is his boy friend, Kazuma Kuwabara, was kidnapped by the very demon who killed her. It's not like he was upset over Keiko's death; with what she had done to his best friend now lover's life he was more upset at not killing her first. However, because of this reason and the fact it was a demon that committed both the murder and the kidnapping he has no evidence to prove he is innocent. How can he explain he didn't commit the crime but it was a demon?

**Warnings:**

This story contains the following and is rated NC-17 for mature audiences.

Course Language, Suggestive Dialogue, Violence, Yaio, Yuri, Character Death major and minor, Original Characters, may contain Out-of-Character moments for both **CSI **and **Yu Yu Hakusho** people, cross pairings, M/F/F, and Descriptive Scenes

_more will be added as story progresses and as needed_

**Author Note:**

Hey everyone!

Yes I know. Another story, but this one has been driving me crazy for a while so I decided to at least give you guys the Prologue to see if you guys are interested. Sorry for not updating anything but I've been having issues with certain off the computer stuff, at work and just love life issues ; so yeah stressed much?

But on the other hand, my juices are flowing again which is a good thing . So something good came out of all of it, so far.

This is my first **CSI **story, and it's my second crossover (_first animated/real TV crossover)_ so please don't be too harsh on me.

The story to this idea is it's really a two part saga. This is really the ending part of what lead to this story. However, it will still make sense and I will make the prequel to this after this story hahaha. There will be hints in this to what happened to lead up to where they are, but nothing too big to ruin the prequel.

I hope you guys enjoy this small taste of what I have so far and please give me some feed back on this because I'm really hoping this turns out as well as I want it to be; or rather think in my mind it will be.

**Enjoy!!**

* * *

Prologue

Lights were a blur together as the night life of Sin City began. Each casino had its own flare to it, attracting customers with high hopes and deep pockets. If the lights didn't draw you in, the sounds and smells sure would. It wasn't called Sin City for nothing; having hookers, gambling, drinks, and the occasional murder.

In the parking lot of one of the grand casinos a female lay on her stomach. Crimson colored liquid flowing at a steady pace from her head, which was turned at a funny angle. The liquid's flow continued, causing a small pool to form around her head and spreading out further. Her long brown hair covered her back, sides, and her face. Her skirt was scrunched up a little, showing off her silky legs; her feet bare and small. Her shirt was a bit wrinkled, yet a bit tight, showing off her nice shape.

Not too far from the woman were her missing heels. They were on their side and had some space between them. However, not too far from the shoes; a good fifteen to twenty feet, stood a man. He would have been considered a drop dead sex god if it wasn't for the fact he was shaking like a leaf and a bit pale. Sweat began to make its way down his face; his chocolate brown eyes wide and full of anger, fear, and helplessness.

His attire was a mess, but didn't look half as bad as he felt at the moment. His white button down shirt wasn't white anymore, red liquid on the front and sleeves; which were rolled up. His arms were well toned and had some of the liquid there as well. His black pants where torn at the knees and dirty.

The poor man shook as if he was cold, which at this time of year shouldn't have been the cause of his chills. He took a few shaky steps forward before falling on to his knees. He stared at the girl who was dead by the amount of blood that was filling the almost empty parking lot.

The man's hands came up to his face, his eyes staring at the shaking blood stained hands of his. His tormented eyes closed as he fisted his dirty hands into his lose jet black hair. His head lowered as a light sob escaped his lips.

"N-no…." a soft voice said. "No…please….K…" the man choked on the words along with his tears that flowed as free as the corpse not too far from where he grieved.

He jerked, turning his head to the sky as if for an answer; opening his mouth wide and making an un-human cry.

"**KUWABARA!!!"**

Sirens filled the air, and soon a small group of curious onlookers showed up onto the scene; the only thing keeping them back being the yellow police tape that told them not to cross.

A black van pulled up onto the scene. A tall man came out from the van wearing a black jacket that had a brown button down shirt underneath, the first two buttons undone. He was a handsome man with some grey on the sides of his dark sand colored hair. He closed the door as he walked brisk yet at a leisure like pace towards the yellow tape. He wore a badge around his neck; stating his name as Gil Grissom from the Las Vegas Crime Lab.

His blue eyes glanced at the policeman who was securing one section of the yellow tape. Grissom nodded at the man who nodded back, recognizing the man. Grissom ducked under the tape and headed towards the corpse. There was another person already at the body, taking pictures of the position of the body as well as anything else that could help in finding the woman's killer.

The photographer was a beautiful young woman with shoulder length brown hair and brown eyes. She wore black pants and a short sleeve black button down vest that had LVPD CSI written on the left breast side of the vest. She also wore a name badge; her said the same information as Grissom's except for her name; Sarah Sidle.

"Hey" she said, not even looking up at the man who was now behind her.

"What did you find so far?" Grissom asked, sliding on a pair of rubber gloves before bending down next to the victim.

"So far, nothing." Sarah said, lowering her camera and watched as he pushed some of the hair back to look at the face.

Grissom's face looked cold as he found the woman's eyes open. Her brown eyes were filled with fear.

"If fear could kill…" he mumbled.

"Excuse me?" she asked, not hearing him.

"Nothing, help me flip her over."

Sarah took off her camera and put it off to the side before kneeling and helping Grissom turn the woman over onto her back. The dead woman's long brown hair seemed to flow around her as the two rested her onto her back as careful as possible. Once that was done, Sarah gasped at the bloody scene, while Grissom looked like he was getting a migraine.

It was amazing the head wasn't disconnected from the rest of the body, since a long deep gash was on her neck, running from her left ear to her right. Her major artery was severed and it was obvious that the poor girl had suffered before passing out from lack of oxygen or lack of blood to her brain; whichever happened first. Either way, it was still a horrible way to die.

"Who found her?" Grissom asked, as he scanned the rest of the woman's body to see if the neck wound was the only injury she sustain; visible that is.

"Actually, it was her boy friend that caught the attention." Sarah said, continuing to take picture after picture, zooming in and out to get better angles and shots.

Grissom raised an eye brow at that response.

"Oh?"

"Yeah." She stopped and held the camera against her chest. "He was crying and screaming about a demon and someone named Kuwabara."

She turned her head, Grissom following her look.

Two men stood away from the scene, yet still within the yellow tape. One was a shaking handsome man. The other was an officer who was an inch taller than the shaking man. He was balding on the top of his head; the only hair left in the back and on the sides. He looked like a veteran and held a way about him that screamed 'Newark, NJ'. His blue eyes looked at the man and then at a small note book he wrote a few notes down in. He also wore a name badge that said Jim Brass; Homicide Detective/ Administrator of CSI.

The man Detective Brass was talking to was shaking a bit and looked like he had dry tear marks on his cheeks. His attitude was calm and seemed to give off an eerie like calm, making Sarah shiver unintentionally.

"Well…" Grissom said, making Sarah turn away from the man towards her boss. "It seems we have a demon lose in Sin City."

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Ok guys, I really hope you liked the prologue! If any of you have ever watched **CSI**, you will notice that I tried to make the prologue have the same feel as the first 5 minutes or so of the show before going into the theme song. . So use your imagination and sing the them song hahaha!

I hope you guys enjoyed it and please review and tell me if I should continue, if the style is ok. I accept constructive criticism and if you flame me I will most likely first cry and then will shrug my shoulders and toss them to the side….that rhymed ; ok no more staying up all night writing for me ; hahaha. Please read and review! Later!!

Chapter Two:


	2. Chapter 2

Hello everyone!!

Sorry for not updating this in a while, but I got stuck on a part and I finally got un-stuck haha. I hope you guys enjoy this chapter .

**See Disclaimer in Chapter One.**

**ENJOY!!**

**Thanks DreamTimeTails for pointing out my spelling mistake sweat drop that usually happens with me, especially when my spell check decided to change what it wants to change haha. Thanks all the same smile**

* * *

Chapter One:

Sirens had gone off in the city full of sin; or otherwise known as Sin City. However; the main focus of the sirens was located near a casino where a woman was murdered.

Detective Brass walked over to the two CSI agents.

"Well," the old time detective sighed when he stopped in front of the two CSIs; Sarah continuing to take pictures while Grissim gave the detective his full attention. "What I got from the guy is that he and this guy named; Kazuma Kuwabara, were walking out after a show…" he began.

_**Flashback**_

_**The young man and another man were laughing and walking as they walked out of the casino. The one named Kazuma Kuwabara was a very tall man; around 6'3" if not 6'5". He had orange hair that was a bit curly and loose. His eyes were small and unless you were able to look close at them; couldn't tell that they were brown. He had high cheek bones; but he was roughly handsome.**_

_**He wore the same thing his companion had, just a light blue button down shirt and brown pants instead of black. He turned to his dark haired companion with a grin; who grinned back.**_

_**"They were walking out when Keiko Yukimura stopped them; our vic." Brass said, looking at the dead girl.**_

_**Back to flash back**_

_**"Hey!" came a female voice from behind the two of them.**_

_**Kazuma froze in some kind of fear, while his friend stopped and looked pissed.**_

_**"Yusuke! How could you?! How could you do this to me and with that…with that bastard!" the woman said.**_

_**The two men turned around, seeing the woman who was now dead standing there alive. She had a scowl on her face, which didn't suit her.**_

_**"No Keiko; how could you do what you did to him?!" Yusuke growled.**_

_**"It's ok Urameshi; really. I'm gonna get a restraining order on her; it'll be fine." Kazuma said, putting his hand on Yusuke's shoulder.**_

_**Yusuke shrugged it off and turned red eyes to his friend.**_

_**"It's not ok damn it! What she did to you…..Kuwabara…..she…." Yusuke started but froze.**_

"They fought for a while when some guy came out from no where and attacked the girl." Brass continued.

_**He felt a strong presence near by, as did Kuwabara. Both boys tensed up.**_

_**Not too far from the girl was an ugly looking thing. He looked human but didn't. He was 7 feet tall with a buffed body that was a puke green color. He would be considered handsome if it wasn't for the skin color and for the sickening look in his eyes.**_

_**The woman looked at the two a bit confused but still pissed.**_

_**"What's wrong? Can't say it?" she said with a smirk.**_

_**"I think its me they are tensed about heh." said the demon.**_

_**Her eyes widened and she turned around. She gasped at the sight of the demon and took a few steps backwards. The demon gave a devil like grin and licked his lips, which caused Keiko to scream and turn around sharply; heading towards Yusuke and Kuwabara.**_

_**Kuwabara's eyes widened as the demon jumped towards the girl; who lost one shoe and then her other as she ran. He watched as she tripped over her other shoe and fell on the ground looking up with fear at her attacker. Yusuke was too stunned at the moment to do anything, and his feelings for his ex were still mixed. Kuwabara knew this and he knew he couldn't let the demon kill Keiko; even if she had done such an awful disgrace to him.**_

"It seems that the victim and our guy over there; who's Yusuke Urameshi by the way; use to be boy friend and girl friend until she raped his best friend and taped it to keep him from seeing her boyfriend." Brass said.

Grissim raised an eyebrow, while Sarah stopped taking pictures and looked at the detective.

"You mean our vic raped her boy friend's best friend?" she asked with doubt.

Brass shook his head, with a weird look on his face.

"I've heard stranger things before, but yeah that's what he told me. So he said he was surprised that his best friend decided to rush to her aid; though he wasn't since he says his friend has this 'honor code' thing; defends damsels in distress or something."

"And who said chivalry is dead?" Grissim said, with amusement in his voice, yet not showing it as he turned to glance at Sarah, who still looked doubtful about what was said.

**_Kazuma screamed Keiko's name before headed over to help her just as the demon's claws grew out while he stood over her frightened form. Kuwabara rushed forward, his best friend now out of his shock and screaming at his best friend; who had out stretched his hand as a glowing sword came forth from it. He screamed as he charged. He ignored the shout from his companion._**

**_The demon turned just in time to dodge the attack. Keiko stared up at the man she had defiled and had hurt. She was shocked that he could protect her and defend her even after what she had done to him._**

**_Yusuke cursed and rushed towards his friend._**

**_"KUWABARA!" he shouted as he ran._**

**_The demon smirked while he held back Kuwabara's sword. He kicked Kuwabara in the stomach; causing the man to cough and dispel his sword; before taking another hit this time in the face. Blood flew out of his mouth as he crashed back into Yusuke; who caught himself enough to catch his best friend and also his lover's fall. He skinned his knee doing so, however it was a small price to pay in his oppinon to make sure his lover wasn't hurt._**

**_A horrible scream caught both of the men's attention and had them look on in horror as the demon picked Keiko up by her hair with a devilish grin on his face. While holding her up by her hair with one hand; he out stretched his claw on his other hand and brought it back. Kuwabara's eyes widened as he saw the claw swing towards Keiko's neck. He pushed himself up off the ground and away from Yusuke who was having a hard time standing._**

**_Kuwabara rushed towards the demon but it was too late. The demon's claw came down across her neck from left to right slicing it. Her eyes widen as everything began to dull around her. The demon dropped her just as Kuwabara with his spirit sword out; swung at the demon again; this time with more force._**

**_The woman fell to her knees, blood in her throat as her eyes widened in fear; choking on her own blood. The last thing she saw was the man she had hurt; the man that she had humiliated and tried to destroy, attacking the thing that had just killed her. Her body fell face first onto the ground._**

**_Kazuma swiped again, but found the demon was too fast._**

**_"KUWABARA!!" cried Yusuke as he stumbled to his feet and began to ran after the two who continued to fight; Kuwabara continuing to attack the demon while the demon moved away._**

**_"You are the one with the Jigen Tou and the lover of the infamous Yusuke Urameshi." The demon said while dodging another attack from Kuwabara._**

**_"I'm also the man that will avenge Keiko-chan's death you bastard! She didn't deserve it! No one deserved a death like that!" Kuwabara screamed before getting a hit on the demon across his face._**

**_The demon screamed while jumping back away to hold his now bleeding wound._**

**_"You'll pay for that human!" he growled before disappearing for a few moments._**

**_Kuwabara's eyes widen as he stood still waiting for the demon to appear. Yusuke was only ten feet now. However just before Yusuke could reach him, the demon appeared and grabbing Kuwabara from behind while digging his claws into his back._**

**_"If you struggle; I'll kill you here and in front of your lover." He whispered._**

"It seemed the murderer heard that Mr. Kuwabara had won a lot of money in his law suit against Miss Yukimura and wanted the money; so he kidnapped him." Brass added.

**_Kuwabara stopped struggling and looked over to Yusuke with fear in his eyes. Yusuke froze where he was, not sure what to do. Kuwabara gave his best friend and now lover a smile before the demon knocked him out with a gas he let out around them, before disappearing._**

**_End Flashback_**

"And then the guy escaped." Detective Brass said. "But that's not the best part."

"Oh?" Grissim said, interested in how this could get better.

"It seems this Mr. Kuwabara fellow is Mr. Urameshi's boy friend."

Grissim raised an eyebrow, while Sarah looked interested.

"So Mr. Urameshi watched the death of his ex-girl friend and the kidnapping of his boy friend?" Grissim said.

He turned and looked at the man, who was much calmer and looked to be talking to someone on a cell phone. Grissim turned to Sarah.

"Would you like to do the honors?" he asked, having his hand wave in the direction of the '_boy friend'_.

Sarah looked at her boss like he was nuts.

"No offense, but he gives me the creeps." Sarah said.

"Well, no offense, but I still need to look over the body." Grissim said leaving no room for her to argue.

She sighed as she handed her camera to the smirking Grissim, before walked over to the man. Grissom watched her for a few moments before turning his face back to the dead body. He leaned down and took several more pictures; making sure to get full detail of how the body looked before it could be processed.

As he was getting ready for another shot, he noticed a few drops of blood, along with a green substance facing the girl's backside, the opposite side of where her blood bleed into the mini pool. Grissim furrowed his eye brows in thought as he bent down to take a closer look. He reached into his pocket, having the camera hanging around his neck as he pulled out some tweezers. He picked up the flaking green substances and examined it, raising his eyebrow at the fact it looked like skin. He pulled out an evidence bag and dropped the sample into the bag.

Meanwhile, Sarah walked up to the guy, who was still talking on his cell phone.

"I know it's risky, but it's Kuwabara damn it! Can't you **TRY** to help?! If not for me…then…then for him?" Yusuke said, as Sarah approached.

He eyed her for a moment, before lowering his voice.

"I got to go…just **PLEASE** think about what I said, ok?" he said before hanging up his cell phone and looking at the new person.

"Am I done here or what?" he said annoyed.

Sarah raised an eyebrow at the guy's aggressive behavior, but shrugged it off.

"I'm Sarah Sidle from the Crime Lab." She said.

"And I'm Yusuke Urameshi, don't you have that already?" Snorted the guy before reaching into this pocket and pulling out a packet of cigarettes.

It could be seen on Sarah's face that she was trying her best to not be rude.

"Well, Mr. Urameshi, I don't want to waste anymore of your '_puresious_' time; however, I still have a job to do. Let me do it so we can catch the guy that did this." She said. "You really shouldn't be smoking those."

Yusuke ran a hand through his loose hair and puffed on his cigarette.

"Ms. Sidle, right? I've been through hell and back. I think I **DESERVE** a fucking smoke right now; don't you think?" He said before letting the cigarette hang in his mouth as he crossed his arms over his chest, giving her an attitude with his eyes as well as his demeanor.

"And besides, what else do you need? A blood sample?!

"If I think it would help; then yes." Sarah said with a grim smile on her face; annoyance in her voice. "I understand you're upset, but you don't have to talk to me like that. I'm only doing my job."

She thought a minute before thinking about the call the man had made not too long ago.

"Who was it you just called?" Sarah asked.

"None of yer damn business, lady." Yusuke growled, glaring at Sarah.

"That's Ms. Sidle to you, and anything related to this investigation **IS** my business Mr. Urameshi."

Yusuke looked at her for a moment before letting out a breath, some smoke from his cigarette passing through his lips.

"I didn't mean to say that…I did, but not that harsh. Kuwabara would have hit me and made me apologize for saying that to a lady…" Yusuke said before his eyes darkened a bit in sadness.

Sarah's own eyes softened. She could tell that no matter how calm he looked on the outside, it was taking a toll on him inside. Yusuke sighed and tossed his cigarette onto the ground before stepping on it.

"If we're done here, can I go? I got to tell his sister and I rather tell her in person then over the phone." He said, his eyes becoming tired from all that had happened; it all finally catching up with him.

"I can't decide that, however; if you let me do my job; you'll get out of here faster." She said, hoping she didn't have to deal any more with this guy.

He seriously was giving her the creeps and even though she kept telling her self it was because of how he had acted so calm earlier; she couldn't shake off the feeling.

Yusuke sighed while running his hand through his hair again.

"Fine, what do you need from me?"

Sarah smiled, happy that she won. She opened up her kit; which she had on her shoulder the entire time, and took out a swab.

"I wasn't kidding about needing the sample. Open your mouth please."

To Sarah, it looked like Mr. Urameshi was going to protest but then decided against it. He sighed and opened his mouth, causing her smile to grow wider.

"That's a good boy." She said, before swabbing the inside of his mouth and then dropping it into an evidence bag. "That wasn't so bad now was it?"

"What else do you need?" he asked a bit annoyed.

"Well, I do need your clothes."

"Why?"

"It's part of the routine." She said.

He sighed.

"Fine, just let me call a friend to drop off some clothes ok? I really need to talk to Kuwabara's sister…" he said with a sigh.

Sarah shook her head.

"We have spare clothes for you to change into in the van; if you want to change there, feel free."

Yusuke sighed.

"Fine, then I can go?" he asked, a pled in his eyes.

He was tired and needed to talk to Shizuru about her brother.

"Yes." She said. "Just follow this nice man over there and he'll escort you to your 'dressing room'."

Yusuke snorted and followed the nice looking police officer to the black van.

_**Scene Change**_

In a building, in the heart of the city; sat a man with long red hair. He was 6 feet tall; but couldn't be seen by the fact he was sitting down in a small lab area. He wore glasses which covered his brilliant green eyes which looked troubled. He stared at a computer screen, tapping his pen on the table.

Right next to the red head was another man. He had dirty blonde hair, which was spiked up. He was around 5'10" and had his headphones on, and nodding his head to the beat of what seemed to be a heavy metal band. He was in the middle of processing some samples he had gotten earlier from one of the other CSI's cases.

That is until Grissim came in.

"Kurama."

The red head turned around from his computer and looked at his boss. His companion continued to listen to his music, not noticing that their boss had just come in.

"I have some evidence I need you and Greg to process…" Grissim said, before turning his attention to the young level-three lab tech; who was head banging.

Kurama smiled. He never thought working for a crime lab could be so…fun. He smirked as he watched his boss stroll up behind his lab partner and look down at him with a raised eyebrow. Greg never the wiser.

As Greg got into a drum solo, or so it appeared to be, Grissim turned off the CD player that was on the counter. Greg continued to drum for a moment before realizing that the music had stopped. He looked over at Kurama who looked to be trying to hold in his laughter. He then looked behind him finding his boss.

He gave his boss a charming yet goofy smile.

"If you are done with pretending to be a rock star Greg, I would like to see you work on something other then air drums." Grissim said.

"Whatcha got?" Greg said, spinning around in his chair to face his boss.

He handed his lab tech the green skin-like sample he retrieved at the scene he just left.

"I want you and Kurama to analyze this."

Greg took it and looked at it, with an intrigued look.

"Never seen anything like this before."

Kurama furrowed his eyes for a moment, in thought; which didn't go unnoticed by his boss.

"I'm guessing this is top priority then right?" Greg asked, looking up at his boss.

Grissim just raised his eyebrow and tilted his head slightly with his cocky grin. Without another word, he left the lab. Greg sighed and got up from his chair stretching a bit.

"Well, time to get to work."

"You mean you weren't before?" Kurama asked with a smirk on his thin lips.

"Oh no I was working...working on my fabulous drum solo." Greg said before laughing.

Kurama laughed too. However, he looked back at the evidence that they needed to process.

'_I'll do all I can Yusuke…_' he thought before watching Greg pop his CD into the stereo system and pump it up all the way.

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Well, I hope you guys liked this! Please read and review! 


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